For many years, the standard apparatus for performing the evacuation of the pleural cavity was a drainage system known as the "3-bottle set-up" which includes a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient's pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also usually prevents the back flow of air into the chest cavity.
Suction pressure is usually provided by a central vacuum supply in a hospital so as to permit withdrawal of fluids such as blood, water and gas from a patient's pleural cavity by establishing a pressure differential between the suction source and the internal pressure in the patient. Such suction pressure and pressure differentials must be precisely maintained because of the dangerous conditions which could result if unduly high or low pressure differentials should occur. However, the hospital suction source typically can vary over time which degrades the suction performance. Also, drainage systems incorporating water filled manometers in the suction control chamber whose water level indicates fluid pressure are inconvenient because of the need to add water prior to use, as well as because of their size and weight. In addition, evaporation in the suction control chamber results in suction pressure variations which must be corrected by the addition of more water thereby increasing the maintenance and monitoring time required in the use of such drainage systems.
Also various inefficiencies have existed in the 3-bottle set-up resulting from the many separate components and the large number (usually 16 or 17) of connections, such as pneumothorax which may result from the loss of the water seal in the water seal bottle if suction were temporarily disconnected, and possible build-ups of positive pressure which could cause tension pneumothorax and possible mediastanal shift. Another serious shortcoming of the 3-bottle set-up is the possibility of incorrect connection and the time necessary to set the system up to monitor its operation.
The 3-bottle set-up lost favor with the introduction of an underwater seal drainage system sold under the name "Pleur-evac.RTM. in 1966 by Deknatel Inc..sup.1 U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and Re. 29,877 are directed to various aspects of the Pleur-evac.RTM. system which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals and hospital laboratories. Such variations include bottle size, tube length and diameter, stopper material and the like. .sup.1 A more detailed description of the need for and the proper use of chest drainage devices is presented in the Deknatel Inc. Pleur-evac.RTM. publication entitled "Physiology of the Chest and Thoracic Catheters; Chest Drainage Systems No. 1 of a series from Deknatel" (1985) which is incorporated herein in its entirety.
Among the features of the Pleur-evac.RTM. system which provide its improved performance are employment of 3-bottle techniques in a single, pre-formed, self-contained unit. The desired values of suction are generally established by the levels of water in the suction control bottle and the water seal bottle. These levels are filled according to specified values prior to the application of the system to the patient. A special valve referred to as the "High Negativity Valve" is included which is employed when the patient's negativity becomes sufficient to threaten loss of the water seal. Also, a "Positive Pressure Release Valve" in the large arm of the water seal chamber works to prevent a tension pneumothorax when pressure in the large arm of the water seal exceeds a prescribed value because of suction malfunction, accidental clamping or occlusion of the suction tube. The Pleur-evac.RTM. system is disposable and helps in the battle to control cross-contamination.
Despite the advantages of the Pleur-evac.RTM. system over the 3-bottle set-up and the general acceptance of the device in the medical community, there remains a continuing need to improve the convenience and performance of chest drainage systems and to render such systems compact. As noted above, fluid filled suction control chambers require the filling of manometer tubes to levels specified by the physician prior to being connected to the patient and the hospital suction system. Although it is conceivable that such filling could be performed at a manufacturing facility prior to shipment, as a practical matter this is undesirable because frequent adjustments may be needed according to the different values of patient suction as dictated by the attending physician. Moreover, the presence of fluid in the various tubes could result in damage to the system during shipment due to freezing temperatures or because of leakage. Furthermore, the levels of suction obtained by a chest drainage system are somewhat limited by the size of the manometer tubes required to maintain such suction levels. For high levels of suction, the size of manometers required would in some circumstances render the drainage system impractical. A reduction in size of the system would offer such benefits as ease of use, ease of storage, less expensive shipping costs, and the reduction in the obstruction between the patient, and visitors and the medical staff. In addition, accuracy of present underwater drainage systems is limited in that the various manometers employed must be constantly monitored visually by observing the liquid level in the respective chambers. Even when gauges are used, they likewise must be constantly monitored. In either case, when the fluid in the manometers evaporates, suction variations occur which require the addition of more water to compensate for the loss. All such activity of course is time consuming.
We have invented an improved drainage device which provides additional improvements to presently available devices.